title: Full color modulation of firefly luciferase through engineering with unified Stark effect.
abstract: The firefly luciferase has been a unique marking tool used in various bioimaging techniques. Extensive color modulation is strongly required to meet special marking demands; however, intentional and accurate wavelength tuning has yet to be achieved. Here, we demonstrate that the color shift of the firefly chromophore (OxyLH2-1) by internal and external fields can be described as a unified Stark shift. Electrostatic microenvironmental effects on fluorescent spectroscopy are modeled in vacuo through effective electric fields by using time-dependent density functional theory. A complete visible fluorescence spectrum of firefly chromophore is depicted, which enables one to control the emission in a specific color. As an application, the widely observed pH-correlated color shift is proved to be associated with the local Stark field generated by the trace water-ions (vicinal hydronium and hydroxide ions) at active sites close to the OxyLH2-1.
authors.affiliation: Fujian Key Laboratory of Semiconductor Materials and Applications, Department of Physics, Xiamen University , Xiamen 361005, China.
authors.forename: Duanjun
authors.initials: D
authors.lastname: Cai
authors.forename: Miguel A L
authors.initials: MA
authors.lastname: Marques
authors.forename: Fernando
authors.initials: F
authors.lastname: Nogueira
mesh_terms: D000818:Animals; D003116:Color; D048888:Fireflies / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D006878:Hydroxides / Q000737:chemistry; D007211:Indoles / Q000737:chemistry; D049409:Luciferases, Firefly / Q000737:chemistry* / Q000378:metabolism*; D010084:Oxidation-Reduction; D011719:Pyrazines / Q000737:chemistry; D011789:Quantum Theory; D013050:Spectrometry, Fluorescence; D055672:Static Electricity; D014867:Water / Q000737:chemistry
chemical_list: D006878:Hydroxides; D007211:Indoles; D011719:Pyrazines; D014867:Water; C014730:oxyluciferin; C031356:hydroxide ion; D049409:Luciferases, Firefly